BFS只拿了20分，各位大佬帮忙看看

#include<bits/stdc++.h>
using namespace std;
struct as{
    int x,y,fx; 
}z[10010],q1,q2;
int t=0,w=0,s1,s2,n;
int z1,z2;
bool b[101][101];
int f[101][101];
char Map[101][101];
int fx1[4]={1,-1,0,0};
int fx2[4]={0,0,1,-1};
void push(int x,int y,int fx){
    b[x][y]=1;
    q1.x=x,q1.y=y,q1.fx=fx;
    z[t++]=q1;
}
as top(){
    return z[w++];
}
int Fx(int x1,int y1,int x2,int y2){//←1↓2→3↑4 
    if(x1<x2)return 1;
    else if(x1>x2)return 3;
    else if(y1<y2)return 4;
    else return 2;
}
void In(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>Map[i][j];
            if(Map[i][j]=='A')s1=i,s2=j;
            if(Map[i][j]=='B')z1=i,z2=j;
        }
    }
}
void Work(){
    memset(f,0x3f,sizeof(f));
    push(s1,s2,0);
    f[s1][s2]=0;
    while(t-w>0){
        q2=top();
        int x=q2.x,y=q2.y,fx=q2.fx;
//      cout<<x<<" "<<y<<" "<<f[x][y]<<endl;
        for(int i=0;i<4;i++){
            int u=x+fx1[i],v=y+fx2[i];
            int fxt=Fx(x,y,u,v);
            if(u>=1&&u<=n&&v>=1&&v<=n){
                if(Map[u][v]!='x'&&!b[u][v]){
                    b[u][v]=1;
                    push(u,v,fxt);
                    if(fxt==fx){
                        if(f[u][v]>f[x][y])f[u][v]=f[x][y];
                    }else{
                        if(f[u][v]>f[x][y]+1)f[u][v]=f[x][y]+1;
                    }
                }
            }
        }
    }
    cout<<f[z1][z2]-1<<endl;
}
int main(){
    In();
    Work();
    return 0;
}